Structure of Al-humic flocs and their removal at slightly acidic and neutral pH
Structure of Al-humic flocs and their removal at slightly acidic and neutral pH
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DOI：
10.2166/ws.2002.0051
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发表时间：
2002-04
期刊：
影响因子：
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通讯作者：
Xu-dong Wang;P. Jin;J. Gregory
中科院分区：
文献类型：
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作者：
Xu-dong Wang;P. Jin;J. Gregory
利用显微和光学监测技术，结合图像分析、高效液相色谱、Zeta电位、总有机碳和紫外吸收光谱等技术，对腐植酸类物质的混凝过程进行了研究，重点考察了絮体的结构、沉降性能和过滤性能。结果表明，pH为5.0时形成的Al-腐植酸絮体较致密，分维较高，而在pH为7.0时形成的Al-腐殖质絮体较疏松，分维较低。在生长过程中，腐植酸铝絮凝体的分维值也有所降低。在两种pH值下，TOC的最佳投加量都在40-50%左右，但pH 7.0时的最佳铝投加量是pH 5.0时的5倍左右。在pH为5.0的条件下，电荷中和是主要的混凝机制，在pH为7.0和pH为5.0的过量投药条件下，扫掠混凝起主要作用。
Using microscopic and optical monitoring techniques, the process of coagulation of humic substances was studied paying attention to the structure of flocs and their settleability and filterability with information from image analysis, and HPLC, zeta potential, TOC and UV absorbance measurements. The results show that Al-humic flocs formed at pH 5.0 appear more compact with higher fractal dimension while those formed at pH 7.0 are looser with lower fractal dimension. During growth, Al-humic flocs also undergo a decrease in their fractal dimension. The attainable removal of TOC is about 40-50% at both pH values, but the optimum Al dose at pH 7.0 is about 5 times of that at pH 5.0. Charge neutralization is believed to be the main mechanism of coagulation at pH 5.0 and sweep coagulation plays an important role at pH 7.0 as well as at pH 5.0 under an overdosing condition.